Epstein-Barr virus (EBV) is associated with a number of human malignancies, and likely plays a causal role in two endemic tumors: African Burkitt lymphoma (BL) and nasopharyngeal carcinoma (NPC). Clonal EBV can be found in Burkitt's lymphomas, T/NK lymphomas, and post-transplant lymphoproliferative disorders (LPD), as well as some T- and B-cell lymphomas, and half of Hodgkin's lymphomas. In addition, EBV may be involved in the development of other neoplasias, including AIDS-related sarcomas, and gastric carcinomas, and certain breast carcinomas. However, we have demonstrated that merely the very presence of the virus in a tumor provides the opportunity for a targeted therapeutic strategy. EBV persists in these tumors in a dormant or latent state. Many Herpes-family virus-infected cells can be killed by nucleoside analog antiviral pro-drugs like ganciclovir, which targe the viral thymidine kinase (TK) enzyme. EBV is resistant to these antiviral agents because latently-infected tumor cells do not express the viral (TK) enzyme. We have demonstrated that selected agents which induce the EBV-TK gene expression in the tumor cells renders the tumor susceptible to standard anti-viral agents. This is a tumor-targeted therapy, in that only the tumor cells (containing EBV) are killed - normal cells are spared. We have conducted a successful Phase I/II study of this virus-targeted therapeutic approach in patients with EBV-associated lymphoid malignancies, all of which were resistant to conventional radiation and chemotherapy. Our targeted therapy produced complete clinical responses (CRs) in 26% of patients, and good partial responses (PRs) in an additional 40% within one treatment cycle (total tumor response rate of 67%). This is an exceptionally high rate of response, and the adverse event profile was favorable. The overall goal of this SBIR proposal is to develop a more potent, more selective, and more patient-accessible virus-targeted therapeutic for testing in EBV+ malignancies. In our Phase I period, we have screened, validated, and selected a highly-potent, clinical-stage lead inducing agent, which is orally-available and has significant human safety data, for use in combination with an anti-viral agent for EBV lymphomas. In this Phase II proposal, we will complete the preclinical development of the virus-inducing agent for this specific indication, generate data to expand its potential therapeutic application and value, and prepare for a Phase II proof-of-concept clinical trial. Our Specific Aims in this Phase II Proposal are: 1.) Optimize lead compound - Refine this EBV/KSHV-targeted therapeutic regimen in animal models; 2.) Expand application of this therapeutic approach into other herpesvirus-associated malignancies; 3.) Complete pre-clinical development; 4.) Clinical trial planning and set-up. Measurable Outcomes and Deliverables: i.) Optimization of treatment regimen; ii.) Validation of this virus-targeted approach in other malignancies associated with ?-herpesviruses; iii.) Complete pre-clinical development of lead compound; iv.) Filing of IND for phase II clinical trial.